DNS CNAME Records Explained: An Alias for Another Hostname

The six points in the video

This is a silent video. The headings, explanations and labels below reproduce the information on screen.

1. 1

   Step 1: CNAME means canonical name

   0:18

   The record identifies another hostname as the alias target.

   On-screen labels: Alias hostname; Canonical target; DNS record.

2. 2

   Step 2: The target is a hostname

   0:30

   A CNAME value is a name rather than a direct IP address.

   On-screen labels: Target name; Further DNS lookup; Resolved destination.

3. 3

   Step 3: A service may supply the value

   0:42

   Use the exact hostname specified by the hosting platform.

   On-screen labels: Provider instructions; Exact target; Correct record name.

4. 4

   Step 4: An alias is not a redirect

   0:54

   DNS does not by itself change the browser address to another URL.

   On-screen labels: DNS name resolution; Browser address; Separate HTTP redirect.

5. 5

   Step 5: Record combinations have limits

   1:06

   Other records at the same name can conflict with a CNAME.

   On-screen labels: Same record name; Existing records; Provider-specific behaviour.

6. 6

   Step 6: Test the served website

   1:18

   The destination service must recognise the original hostname too.

   On-screen labels: Alias resolution; Host configuration; Expected content.

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